The invention of the present patent application relates to an image forming apparatus such as a copying machine and a printer each forming an image by using an electrophotographic method in which a cleaning section that is composed of a blade is equipped on each of an intermediate transfer member and a secondary transfer section.
In the image forming apparatus such as a copying machine or a printer that forms an image by using electrophotographic method, charging, exposure and developing processing, for example, are carried out on an image carrier that is composed of a photoconductor drum, and a toner image is formed. After that, the aforesaid toner image is transferred onto a transfer material, or, a toner image after being transferred onto an intermediate transfer member composed of, for example, a belt, is transferred onto a toner image (secondary transfer), and after that, there is a structure wherein fixing processing is conducted and a toner image is fixed on a transfer material. The image forming apparatus of this kind is equipped with a cleaning blade (hereinafter called as a blade simply) for cleaning the surface of the intermediate transfer member.
Meanwhile, there is known a problem of turning up of a blade which is one of problems that take place when a blade is used as a cleaning section, and it is well-known as a measure for the problem that an appropriate amount of toner that does not affect ordinary image forming is given to the blade.
For example, Unexamined Japanese Patent Application Publication No. 2007-240768 discloses an image forming apparatus having the structure wherein color toner images formed on four photoconductors are composed on an intermediate transfer belt, and then, are transferred onto a transfer material. Further, a blade is provided for the image carrier that is composed of a photoconductor or an intermediate transfer belt. And, with respect to toner supply for the blade, distribution of total number of pixels relating to the sub-scanning direction of images formed on the image carrier, for example, is calculated, and a patch pattern of toner is formed on a non-image area on the image carrier that corresponds to a pixel section that is less than a prescribed threshold value in the aforesaid distribution. After that, toner that is forming the patch pattern is conveyed to the blade without being transferred onto the transfer material, to be accomplished. (As a result, sliding of the blade on an edge portion for the image carrier is maintained to be in an excellent state, to prevent turning up of the blade, and the cleaning capacity of the blade is maintained.)
Unexamined Japanese Patent Application Publication No. H11-272135 discloses the image forming apparatus that is equipped with a transfer belt that is caused to travel along the image carrier and conveys a transfer material to a developer image on the image carrier. The aforesaid image forming apparatus has a blade provided for the transfer belt and an exposure device that forms a line image for supplying toner serving as a lubricant to the transfer belt. And, supplying toner to the blade is accomplished by forming a line image on the image carrier in the case of initializing the apparatus and by conveying toner in a quantity adjusted by the number of conveyed transfer materials through the transfer belt to the blade. (An achievement of an excellent cleaning power corresponding to a degree of damage of the transfer belt and a prevention of turning up of a blade are targeted.)
Unexamined Japanese Patent Application Publication No. 2000-19920 discloses the image forming apparatus that has therein a transfer belt and a blade provided on each of the image carrier and the transfer belt. An image forming on the transfer material is carried out when color images in various colors are recorded successively on transfer materials on a multiple superimposing recording basis. And, with respect to toner supply for the blade, it is accomplished by watching an amount of toner adhesion for each of areas divided into plurality in the main scanning direction of the image carrier, by setting a toner adhesion mode in case of need, and by supplying toner in an appropriate amount to a non-image area on the image carrier, corresponding to an area where toner supply is required.
Though constitutions of image forming apparatuses disclosed in Unexamined Japanese Patent Application Publication Nos. 2007-240768, H11-272135 and 2000-19920 are different from each other, various technologies for preventing blade turning up in the constitutions are guessed to be extremely useful. However, a target on which a blade is to be provided is an image carrier composed of a photoconductor and a transfer belt that conveys a transfer material, or an intermediate transfer member onto which a toner image formed on the image carrier is to be transferred, and constitutions other than the aforesaid items are not considered, which lacks a multiplicity of uses.
On the other hand, as a configuration of an image forming apparatus, there is considered the constitution wherein a belt-shaped toner patch (hereinafter, referred to as a patch image) is prepared on a non-image area of the image carrier corresponding to a transfer material clearance, for example, and it is caused to be transferred onto a secondary transfer device such as a roller through an intermediate transfer member. Specifically, a turning up of a blade is prevented by causing toner that forms the aforesaid patch image to be moved on a secondary transfer section such as a roller through the intermediate transfer member and by supplying toner to the blade provided on the surface of the secondary transfer section to be touched. Further, the patch image is made to be a belt-shaped image having a length that covers the total length of the blade. Incidentally, the aforesaid patch image may either be one that is utilized as a factor for acquiring stabilization of image density such as, for example, developing voltage control, or be one that is supplied to the blade of the secondary transfer section to be used only for the purpose to prevent turning up of a blade. The image forming apparatus having the constitution of this type can maintain high productivity, and it is expected to offer high image quality in color image forming.
However, when the constitution is made to be one wherein a blade is provided also for the secondary transfer section, in addition to a blade provided to correspond to the intermediate transfer member, it is impossible to prevent turning up of the blade if toner is not supplied to both blades stably. But then, if it is tried to fulfill an amount of toner supply, there is no option but to increase an amount of toner consumed to form patch image inevitably, and further, in some cases, it is impossible to supply toner between transfer materials, and it is forced to suspend print operations, resulting in a fault that high productivity cannot be maintained.